There exists a technique of receiving a sound wave (speaking voice, etc.) containing a noise with a microphone and eliminating a noise component from an output signal of the microphone. For example, Nonpatent Document 1 describes a study on elimination of the noise component.    Nonpatent Document 1: Amitani and others, SHINGAKUGIHOU, US84-98, pp. 41-46, January 2002.